Turbine casing construction



Sept., 18, 1956 c J. McDowALL ETAL 2,763,462

TURBINE: CASING CONSTRUCTION 5 Sheets-Sheet l Filed Jan. 11, 1950 Sepi-3 1955 c. J. McDowALL x-:TAL 2,763,462

TURBINE CASING CONSTRUCTION y 5 Sheets-Sheet 2 Filed Jan. ll, 1950 www(,mf ff f i I I I l I l I 3 Wi@ ww l JW Y m a@ m B m n K A -IHN M, MM. Q

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TURBINE CASING CONSTRUCTION Filed Jan. l1

5 Sheets-Sheet 3 Sept. 18, 1,956 c. J. McDowALl. ET AL 2,763,462

TURBINE CSING CONSTRUCTION 5 Sheets-Sheet 4 Filed Jan.. l1, 1950 mwN Sem38, 1956 c. J. MoDowALl. ETAL 2,763,462

TURBINE CASING CONSTRUCTION 5 Sheets-Sheet 5 Filed Jan. ll ,A1950 Bg@der Wa/View? ilnited States Patent O TURBINE CASING CONSTRUCTIONCharles J. McDowall and Oscar V. Montieth, Indianapolis, Ind., assignorsto General Motors Corporation, Detroit, Mich., a corporation of DelawareApplication January 11, 1950, Serial No. 138,026

8 Claims. (Cl. 253-78) This invention relates to combustion engines andmore patricularly to axial ow .gas turbine power plants.

This invention relates to an axial ilow compressor turbine power unit,which provides a propeller drive and a supplemental jet power source.The compressor turbine unit is mounted coaxially on the same shatt withthe -compressor at the forward end. The propeller is connected to theforward end of the compressor. The air passes over suitable fairing andenters the axial llow compressor where it is compressed. Then the mainportion of the air enters the combustion chamber or burner and theremainder passes around the combustion chamoer to cool it. Thecombustion chamber is expansible and is mounted o-n fixed supports atthe forward end and in a splined support to allow axial sliding due toexpansion at the rear end. The complete compressor turbine power unit issupported from a torque ring which is centrally located. A cylindricalshell is secured to the torque ring and extends rearwardly surroundingthe turbine unit, and provides an outboard support for the rear bearing.The stator turbine blading comprises a series of `segments withinterengaging tongues which interiit in a series of annular rings. aresecured together to provide the exterior conical casing for the turbine.rihis casing is supported by a splined joint with the cylindrical shell,The rotor wheels are secured to the main shaft 'by suitable splines, andare centered about the shaft by annular wedge-shaped elements engagingeach side of the wheels. The wheels supp-ort suitable turbine rotorblades which rotate between the stator blades.

The primary object of this invention is to provide a supportingstructure for a compressor turbine power unit with provision forexpansion in the power unit.

Another object of the invention is to provide in a compressor turbinepower unit a burner or combustion chamber having a fixed support at oneend and an axially sliding support at the other end, in order to providefor relative expansion ybetween the combustion chamber and the otherportions of the power plant.

Another object of the invention is to provide in a turbine used in aninternal combustion engine power plant a supporting shell `surroundingthe turbine and connected to the turbine by means of a splined joint,and bearing support means secured to the turbine casing to support therear end of the main shaft and to provide relative expansion of the-shell and casing.

Another object of the invention is to provide in a rotary machine aconical housing formed of a plurality of stepped ring sections securedtogether and having a conical lining or fairing inside formed of aplurality of annular segment sections secured to the inside of saidrings.

Another object of the invention is to provide in a rotary machine a.generally conical housing formed of a plurality of rings of increasingdiameter secured together and having axially directed internal flangelips to support an inner fairing or lining consisting of a plurality Theannular rings 'ice of annular segmental members having axially directedannular hooks engaging said lips to support and position said fairingmembers within said casing.

These and other objects of the invention will be more apparent from thefollowing description and drawings of a preferred embodiment of theinvention.

In the drawings,

Figure 1 is an elevation View with parts in section of the compressorturbine power unit.

vFigure 2 is a fragmentary enlarged elevation with parts in section ofthe combustion chamber.

AFigure 3 is a fragmentary enlarged elevation with parts in section ofthe turbine unit and blading.

Figure 4 is a fragmentary enlarged elevation with parts in section ofthe turbine shaft and turbine wheel con nection.

Figure 5 is a section of Figure l on the line 5 5 with parts brokenaway.

The compressor turbine unit illustrated in the drawing is built around ailoating shaft 10 which is connected at its forward end to a compressorshaft 12. The compressor shaft 12 is rotatably supported by bearing 14mounted in the forward end 15 of the power plant housing 16. The rearportion of the shaft 1b just forward of the turbine is supported androtatably secured to shaft 230 by a spl-ined connection. The end ofshaft 23u adjacent the splined connection is supported by a bearing 18in the rear portion 19 of housing 16. A propeller drive shaft (notshown) may be connected to the forward end of the compressor assembly.The compressor assembly consists of a rear compressor shaft 12 and aseries of wheels 22 which support suitable rotatable compressor blading24 and are held together by the tie rod 20. The air enters through asuitable faired compressor entrance (not shown) and is compressed by thecom pressor rotary blades 24 and stator blades 26 or diffuser vanesmounted in the compressor housing 28. A plurality of combustion chambersor burners 30 are arranged `around shaft 10 between the compressor andturbine. Each burner 3i) has an enlarging passage 32 connecting `asector of the outlet of the compressor to the central cylindricalportion 33 of the burner 3ft. The liner 34 has a central cylindricalportion spaced from the burner 30. The forward end 36 of the liner has areduced diameter and is spaced from the walls of the passage 32 so thata portion of the air flows between the liner 34 and the burner housing36 to cool the liner.

An air baille or llame holder 38 is positioned at the forward end of theliner directly in front of the fuel nozzle 40. The liner 34 is supportedby suitable spaced supports 42 to the burner 30. The forward passageportion 32 of the burner 30 may be formed integral with or secured tothe casing 16. To the rear of the supports 42 the burner housing 30 hasan enclosure 44 formed of `a pair of spaced overlapping wall portionswhich provides protection for a corrugated metal expansion diaphragm 46to seal the joint.- A central portion 48 of the liner 34 has a slidingjoint with the forward end and the rear end 49 of the liner.

The central housing 16 has a central sleeve 5t) and an external sleeve52 extending from the forward bearing support 15 to rear bearing support19. An annular plate 54 surrounds the external sleeve 52 of the housing16 and is rotatably xed by interengaging splines 5S secured to theexternal sleeve 52, The plate 54 is rotatably xed at its outer perimeterto a ring 53 by intel-engaging splines 56 on the outer edge of the plateand the inner edge of the ring. The ring S3 is bolted to the torque ring58. The splines allow axial movement of the annular plate with respectto the ring 53 and the frame 16. The torque ring 58 which has a boxsection is braced by a plurality of diagonal struts 60 suitablyconnected to the ring 58 at spaced intervals and secured to the sleeve52 by brackets 62. Radial bracing struts 64.are secured to strut 60 andthe sleeve 52. The plate 54 has an annularly disposed series of sectorshapedapertures 57 for each one of the combustion chambers 30. As shownon the leftfside 'of Figure and Figure 2, the outer shell 33 of theburner 30 has a flange suitably secured to the sector plate 59. Theplate 59 has a circular aperture for the burner and is secured at itsinner and Vouter edges by suitable means such as bolts 68 to the annularplate 54. The sides of the sector plates 59 seat on the annular plate 54between the apertures 57 and are clamped in position by clamping bars61. As explained above the rear end of the burner 30 is attached to theforward side of the plate 54. The annular series of burner linerportions 49 are surrounded by an annular wall 72. This wall 72 issecured at its forward end tothe rear side of plate 54 by bolts 68 andts over the outer edge of the turbine inlet 92. An inner annular' wall74 is positioned between the burners and the main shaft. This wall 74 issecured at the forward end to the inner edge of plate 54 by bolts andengages the inner edge of the turbine linlet 92. The inner wall 74 andouter wall 72 are concentric with the shaft and provide an annular spacefor the series of rear liner sections 49. A plurality of ducts 76connects the walls 72 and 74 to provide for the passage of cooling airfrom the space between the shaft housing and the inner wall 74 to thespace between outer wall 72 and cylindrical housing 88.

The turbine stator housing 78 is supported at the forward end by theouter portion of an annular plate 80 which is piloted on or slidablysupported on the outer cylindrical portion of the housing at the rearbearing support 19. The rear end of the housing 78 has an annularsplined flange 84 which is slidably supported in an annular flange 86secured to a cylindrical shell 88 supported on the torque ring 58. Thecylindrical shell 88 has an outlet conduit 90 for the cooling air. Thestator housing which is supported at its forward end on the annularplate 80 consists of a plurality of annular rings bolted together. Theplate 80 has near its permimeter an aperture having the shape of anannular segment for each combustion chamber. Each of these apertures isbounded by a wide ilange 92 to support the end of the burner. Referringto Figure 3 for clarity, the iirst external ring 94 of the casing 78 isconnected to the flange 92 of the plate 80 and terminates in a radialflange 96 and axial flange 98. The integral assembly of the plate 80,the flange 92 and ring 94 may be formed by welding the parts together.The first row of stator blading 102 consists of a plurality vof segmentshaving an external rim 104 and an internal rim 106 which fit within theflange 92. The blade segments 102 are circumferentially positioned bythreaded pins 108. The second ring 110 has a recess 112 which seats onthe end of axial flange 98 and a radial flange 114 which engages in faceto face relation the radial llange 96 of the first ring 94. An annularseries of bolts secure flanges 96 and 114 together. The annular ring 110is stepped to provide a small cylindn'cal portion adjacent flange 114and a large cylindrical portion. The ring 110 has adjacent its smalledge an offset axial flange or lip 116 and adjacent the center an offsetaxial llange or lip 118, and adjacent the large edge an ollset axialflange or lip 120. The interior surface of the housing is formed with aplurality of rows of segments to form Ia generally smooth conical shape.The first row of the interior surface of the housing 78 is formed by aplurality of segments 122 which have adjacent each edge axial flanges orhooks 124 and 125 which fit over the lips 116 and 118 respectively ofthe ring 110. A threaded pin 126 prevents rotary displacement of thesegments. A second row of stator blading 128 is formed in segments andis secured to outer ring segments 130 and inner ring segments 132. Theouter ring segments have displaced axial flanges or hooks 134 and 13S.The hook 134 on the smaller side extends over the hook V125 of thepreceding fairing segment 122 and the other hook 135 engages the lip 120at the large end of the ring 110. A pin 136 prevents circumferentialdisplacement of the stator blade segments 128. At the large end of thering a flange 138 having an axial offset portion and main radial portionextending outwardly at the end of the axial portion is provided in orderto secure the ring 110 to the next ring 140.

The second ring 140 has a similar stepped construction to provide asamll cylindrical portion and a large cylindrical portion. At the edgeof the sm-all cylindrical portion a flange 142 having a radial portionand an axial portion extending from the inner edge of the radial portioninterengages the axial and radial portions of flange 138 to position thering 140 with respect to the ring 110. The flanges are secured togetherby means of bolts 144. The ring 14d) has an annular axial flange or lip146 at the center and a similar lip 148 at the large edge. Fairingsegments 150 which are employed to present a smooth conical interiorsurface, have axial flange hooks 152 and 154. The hook 152 at thesmaller side of the ring segment 150 extends over the hook of theprevious stator blade ring 130. These two anges seat against the lip 120of ring 110. At the other side of fairing segment 150 the hook 154 hooksover the llip 146. The pins 156 prevent circumferential displacementbetween the ring and the fairing segments 159. The third row of axialstator blades 158 has a similar outer ring 160 and an inner ring 162.The outer ring has axially disposed flange hooks 164 and 166 which fitover the hook 154 of the preceding fairing segment and over the lip 148of the ring 140 respectively. A threaded pin 167 preventscircumferential movement of blade segment 160. The ring 140 has at itslarger edge a flange 168 having an axially extending portion radiallyoutward from the lip 148 and a radially extending portion at the end ofthe axial portion. The flange 168 is secured by bolts 174 to the ring178 which has a flange 172 having a complementary radial portion andaxial portion extending from the base of the yradial portion. The ringhas a stepped construction with a smaller and a larger cylindricalportion. Between these two portions an axially extending lip 176 isprovided to support the fairing members and blade segments. Fairingmembers 178 of segmental form with conical interior surfaces haveaxially directed flange hooks 180 and 182 at opposite sides. The hook189 overlies ythe hook 166 on the outer ring 160. The axial portion offlange 172 fits over these flanges. The hook 182 hooks over the lip 176to support the other side of the various segments 178. The segments 178are held in Vcircumferential position by the threaded pins 184.

The last row of stator blades 186 is secured between an inner ring 188and an outer ring 190. The outer ring 190 has an axially directed flangehook 192 at one end overlying the llange 182. At the other side of thering 190 the flange 194 extends outwardly from the ring and fits in arecess in the ring member 196. It should be noted that on each of thefairing ring segments and outer blade ring segments the ilange hooks oneach side were directed in the same direction, toward the small end ofthe turbine housing 78. The ring 170 has the flange 198 having an axialportion and a radial portion at the end of the axial portion. The axialportion secures the flange 194 in th'e recess195 and the axial andradial portionsinterfit with axial and radial portions of flange 280 onring 196. Boltsf202- hold these flanges together. A pin v204 positionsthe last row of blades 186 circumferentially. The ring 196 has a flange206 which -is suitably secured and nterlocked by means of axial andradial portions to flange 208 on the supporting ring 210. The supportingring 210 may bemade integral with the splined flange 84which slidablysupports the assembly fromfthe cylindrical shell 88. At the rear of thesupporting ring 210 a jet fairing ring `or tail cone 212 is secured. Aninlet conduit 214 is connected to the jet fairing ring to bring coolingair to the interior of the double wall flow vanes 216.

A radial bearing support strut 218 is secured to the supporting ring 210at the outer end and `at the inner end to the bearing support member220. A diagonal strut 222 extends from the outer end of the radial strut218 to the gusset 224. The gusset 224 is connected by an inner diagonalstrut 226 to the bearing support 220. The gusset 224 supports theinterior ring or wall 228 of the jet passage. As shown in Figure 4 theturbine shaft 230 extends from the central bearing 18 to the rearbearing 232 and is mounted in the bearing support 220. The shaft 230 hasa splined section 234 for each rotary blade wheel. The rotary bladewheels 236, 238, 240 and 242 each support a plurality of rotor bladessecured to the periphery of the wheel. At the rear end of the turbineshaft 230 there is an integral annular abutment 244 and a two pieceannular ring 246 which have tapered surfaces engaging the centralaperture of wheel 242 to center the wheel on the shaft. Similarly wheels240 and 238 are centered on the shaft by engaging the wedge or conicalsurfaces on the two piece annular spacing members 246, 248 and 250. Asshown in Figure l, a similar annular wedge 252 which is secured by theseal member 253 threaded on the shaft 230 engages the forward side ofwheel 236 to center this wheel and tighten all the wheels and theirannular wedges against the integral rear abutment 244. Referring toFigure 3 the wheel 236 extends between stator blades 102 and 128 tosupport rotor blades 254. A ring baffle 256 is secured to wheels 236 and238. The ring baie 256 and the flanges on the ring 132 limit the flowaround the stator blades 128. The wheels 238 and 240 support rotorblades 258 and 264 and baille ring 260 which cooperates with flanges onthe rim 162 to limit the by-pass ow around the stator blades 158. In thesame manner wheels 2410 and 242 support the blades 264 and 265 and ringbaflie 266 which in connection with the flanges on the rim 188 reducesthe by-pass iiow around the stator blades 186.

Just to the rear of the last wheel 242 an annular panel 26S closes thespace between the bearing support 220 and the inner wall 228 of the jetpassage. There are spaces between the strut anchorages in member 220through which air coming from inlet 214 and passing through vanes 216 tothe other side of partition 268 is sucked out between partition 268 andwheel 242 into the flow of gas in the jet passage. This air flow coolsthe rear bearing 232. The bearing support 220 also supports an oil pumphousing and sump 270. The rear end of the oil sump 270 is supported by aradial strut 272 attached to the gusset 224. A gear 274 attached to theend of shaft 230 drives the return oil pump 276 which pumps oil into thespace between the sleeve 278 and the conduit 280. The oil flows from amain oil pump (not shown) through the hollow tie bolt 20 and compressorshaft 12 to lubricate forward bearing 14 and through conduit 280 infloating shaft to lubricate central bearing 18 and through conduit 280in shaft 230 to auxiliary passage 281 Where the oil is sprayed onbearing 232. The conduit 280 acts as a tie bolt to hold shaft 10 andshaft 230 together. At the forward side of bearing 232 a seal 282prevents the flow of oil into the turbine space. The oil lubricatesbearing 232 and drops into sump 270 where pump 276 returns the oilthrough the space between sleeve 278 and conduit 280 to the sump in thebase of bearing support 19. The bearing support 19 has a portionproviding a sump for oil pump 284 which is driven by gear 286 onfloating shaft 10. The pump 284 lifts the oil from the sump in support19 and forces the oil through passage 288 and into pasage 291 in theforward end of the housing 52. The oil from bearing 14 flows into thesump 290 in the lower portion of the bearing support housing 16. A gear292 on shaft 10 drives a gear pump 294 which returns 6 the oil from sump290 to the main oil 'tank through passage 291.

In order to reduce the end thrust on the compressorturbine rotorassembly conduits 300 are provided as shown in Figure l to connect theair space on the rear side of the compressor wheel with the air space onthe forward side of the turbine wheel in order to balance the gasforces. The first turbine wheel 236 as shown in Figure 3 has an axiallyextending flange 302 which extends into a labyrinth seal 304. Coolingair is also circulated through the center of the housing and -around thesleeve 50 by centrifugal impeller blades 306 mounted on the shaft 230close to the forward face of turbine wheel 236. The im` peller blades306 draw air from the center region between sleeve 50 and housing 52past tins 305 and about the bearing 18 and force the air out through thepassage 308 and apertures in partition 309 and through the hollow ducts76 between the burners 30 to the outlet 90 in the cylindrical support88. A flange 312 is secured to the cooling impeller immediately abovethe passage 308 and interts with the annular labyrinth seal element 314on the fan housing to prevent leakage between the cooling air passageand the equalizer passage.

The compressor turbine power unit propels the ship by means of apropeller driven through the compressor rotor assembly mounted on theforward end of the main shaft and of the jet reaction. The air enters atthe forward end of the power unit and is compressed by the compressorunit consisting of rotor blades 24 and stator blades 26, and enters theburners 30 Where fuel is supplied by the nozzle 40. The hot gases arethen produced in the combustion chamber and rapidly flow through thecombustion chamber to the turbine. In the turbine the gases expand anddrive the turbine in the conventional way. Due to the fact that highcombustion heats are localized in the combustion chambers and adjacentthe turbine blading, there is liable to be a large temperature dilerencebetween various parts of the power plant and thus large di'erences inthe expansion of various parts of the machine. In order to permit thisexpansion without destruction or distortion of the power plant theimportant elements of the unit are mounted to allow for expansionbetween them. The burners are fixed at their forward end to the frame 16but are fixed at their rear end in an annular plate which is mounted forsliding movement to allow for expansion. An expansion joint is alsoprovided in each burner 30 to provide for the differential expansionbetween the burners and the frame between the forward end of the housing52 and the annular thrust plate 54. The aft portion of the turbineassembly is supported by the shell 88 by means of the splined connection84-86 in order to allow for differential expansion between the supportmeans andthe turbine assembly. Thus the combustion chamber and theturbine assembly can expand relative to their supports without deformingor straining any portion of the power plant. The turbine wheels aresecured on the turbine shaft 230 by means of interengaging splines 234and are centered with respect to the shaft by means of the annulartwo-piece rings which have wedge shaped portions at each side so thatthe turbine wheels may be wedged into concentric relation with theshaft.

The turbine stator section 78 is formed of a plurality of steppedannular rings which support an internal fairing or lining. A portion ofthis internal fairing is formed by the exteral rings of the statorblades. Each of the casing rings 110, 140 and 170 are stepped to providea small and a large cylindrical section. The rst ring has three axiallydirected flange lips 116, 118 and 120 which provide support for thehooks at each side of fairing segments 122 and fairing and blade supportsegments 130. The second ring has two lips 146 and 148. The fairingsegments have hooks which engage the last lip on the first ring 110 anda lip on the second ring.

The blade ring segment 160 has hooks engaging both lips of the secondring. The third ring 170` has one central Alip 176. The fairing segments178 have hooks engaging the -end lip of ring 1'40 and the lip 4of ring170. The blade ring segments 190 have hooks engaging the lip on ring 170-and final spacer ring 196. This construction provides ka simplearrangement of parts to provide a structure which may be easilyassembled and disassembled for repair from a plurality of simplereplaceable parts.

Certain features of our invention disclosed but not claimed` herein areclaimed in our divisional application Serial No. 572,861, filed March21, 1956, for Gas Turbine Power Plant.

It will be appreciated that the above described embodiment of theinvention fis illustrative of the various features of the invention andthat many modifications of the invention may be made within the scope ofthe appended claims.

We claim:

l. A stator structure for a gas turbine or the like comprising a casing,axially extending lips on the casing defining axially extending recessesbetween the lips and inner surface portions of the casing radiallyspaced from the lips, segmented fairing rings mounted in the casinghaving flanges terminating in axially extending parts, the said parts ofadjacent edges of two adjacent fairing rings being received in a saidrecess, and locating means extending from the casing into each segmentof the fairing rings adapted vtorestrain the segments against axial andcircumferential movement.

2. A structure as defined in claim 1 in which the locat ing means extendthrough the casing and are removable from the exterior of thecasing.

3. AV stator structure for a gas turbine or the like comprising aplurality of casing rings, means for fixing the casing rings together atthe ends thereof' to constitute a casing, axially extending lips on thecasing rings defining axially extending recesses between the lips andinnerl surface portions of a casing ring radially spaced from the lips,fairing rings mounted in the casing having flanges terminating inaxially extending parts, the said parts of adjacent edges of twoadjacent fair-ing rings being received in a said recess, and locatingmeans extending from the casing into the fairing rings adapted 'torestrain the rings against axial and circumferential movement.

4. A structure as recited in claim 3 in which the casing rings are of.progressively increasing diameter toward one end of the casing and thefairing rings are 8 movable` through the casing rings `for removal fromthe said end of the casing.

5. A stator 'structure for a gas turbine or the like comprising aplurality of casing rings, means for fixing the casing'rings 'togetherat the ends thereof to Vconstitute a casing, axially extending lips on`the casing rings defining axial-ly extending recesses between the lipsand inner surface portions of a casing ring radially spaced from thelips, segmented fairing rings mounted in the casing having fiangesterminating in axially extending parts, the said parts of adjacent edgesof two adjacent fairing rings being received in a said recess, andlocating means extending from `the casing into each segment of thefairing rings adapted to restrain the segments against axial andcircumferential movement.

6. A structure as defined in claim 5 in which each casing ring has twolips and mounts two rows of fairing rings.

7. A stator structure for a gas turbine or the like comprising aplurality of casing rings, means for fixing lthe lcasing rings togetherat the ends thereof to constitute a casing, axially extending lips onthe casing rings defining axially extending recesses between the lipsand inner surface portions of a casing ring radially spaced from thelips, and segmented fairing rings mounted in the casing having flangesterminating in axially extending parts, the said parts of adjacent edgesof two adjacent fairing rings being received in a said recess.

8. A stator structure for a gas turbine or the like comprising a casing,axially extending lips on the casing defining axially extending recessesbetween the lips and inner surface portions of the casing radiallyspaced from the lips, and fairing rings mounted in the casing havingflanges terminating in axially extending parts, the said parts ofadjacent edges of two adjacent fairing rings being received in a saidrecess.

Y References Cited in the file of this patent UNITED STATES PATENTS2,282,894 Sheldon May 12, 1942 2,432,359 Streid Dec. 9, 1947 2,458,148Cronstedt I an. 4, 1949 2,461,242 Soderberg Feb. 8, 1949 2,472,062Boestad June 7, 1949 2,479,573 Howard Aug. 23, 1949 2,488,867 JudsonNov. 22, 1949 2,488,875 Morley Nov. 22, 1949 2,494,821 Lombard Jan. 17,1950 2,529,958 Owner Nov. 14, 1950 2,584,899 McLeod Feb. 5, 1952

